raineycd

LD6 are great plugs, so probably not that. What did you gap them to?

Bryce

Driving home, I noticed the oil pressure varied some, but was overall less than normal. Perhaps I have a failing oil pump. Still trying to pull the codes, but the Windows 7 crashes when I plug in my Durametric cable. Been through a clean install twice. Trying it on an XP computer.

I sincerely doubt it's a gapping issue. I set the gap to what people on Renntech suggested. I can't remember the value.

Bryce

Okay, the XP computer worked fine.

P0300: fault code 507 - Misfire detection (total)
P0301: fault code 508 - Misfire cylinder 1
P0302: fault code 509 - Misfire cylinder 2
P0303: fault code 510 - Misfire cylinder 3

Seems like it's half of the engine. Cylinders 1,2,3 are on the passenger side?

PorscheDoc

1,2,3 are on the driver's side.

jpflip

I wonder if it can be a variocam malfunction or the bracket for the valve opening solenoid that is broken...The post on this link from Almo shows you the bracket and the position....http://www.6speedonline.com/forums/9...e-light-2.html

Bryce

Any tips or tricks of things I can do with my Durametric or otherwise to try and diagnose why my misfires could be coming on one side only? Guess it's into the shop for me =(. Bleh.

jpflip

It is possible to test the variocam with Durametric. And you can test both system individually and both banks! Look at the "drive link" section (see pic) After you select the system and you press start , with the engine running, the engine should start rumbling. If it does that mean the system is Ok. Just a drop in RPM is sufficient to show you the solenoid is pressurizing the system you are testing, valve lift or camshaft adjustment.... Durametric shown is 5.1. version 6 got it too but in another menu...

Macster

jpflip gave you good advice when he pointed you to the drivelinks in durametric tool.

I'd do that first.

Be aware you might be fooled into thinking all is ok though cause the problem is intermittent. (My 02 Boxster's VarioCam solenoid and actuator was just replaced. They were intermittently bad but thankfully (?) intermittently bad often enough the diagnosis (by the tech) was easy to make.)

Not sure what to advise in this area. Ideally you'd want to run the engine to the point the symptoms were appearing then test the VarioCam system to catch one of the bad components during its failure mode.

But I'm leery of running a sick engine very long sick while trying to diagnosis the cause of the symptom. I'm always concerned a serious but relatively inexpensive problem will suddenly get much more serious and expensive if the system fails completely. I guess I'm worried about a cam chain skipping a tooth or flopping about and busting a chain guide/tensioner rail, etc.

Another possibility is the MAF is bad. I have encountered at least one other owner of a water cooled modern Porsche (not a Turbo though) that found misfires on one bank were MAF related.

If the Durametric tests don't turn up anything with the VarioCam system you might consider disconnecting the MAF at the wiring harness, clearing the DTCs (to reset all the learned fueling to their defaults) then driving the car to see if the misfire symptoms return. If they do not return and you're convinced you drove the car enough to give the symptoms time to reappear, the MAF is suspect #1. Sure, I agree a long shot that the MAF is bad.

Sincerely,

Macster.

Bryce

Okay, this weekend I had a chance to test the variocam solenoids. After letting the car idle a while and achieve a smooth RPM, I engaged both sides and each had the appropriate dip in RPM and shudder.

I also played with the data logging feature and saw that I was not constantly misfiring, the counter stayed at 0 during my idle of 10 minutes or so.

Does anyone have any ideas about how I might be able to use the data logging feature on a test drive to determine if I have anything wrong? Which values should I monitor?

Otherwise, I will just take the car into the shop. But, if there is a reasonable chance I can still diagnose something, I would like to be able to do it myself.

Bryce

Mac, what's a DTC and how do I reset it? I could try the MAF disconnect. I know where it is and it seems like something easy to try.

Macster

DTC is short for 'diagnostic trouble code'. One (or more) of these are logged when the check engine light is turned on.

I haven't used the Durametric tool but generally there should be a menu option to read error codes (DTCs), and clear them. (There is probably a view freeze frame data menu choice too and one for retrieving any pending DTCs and lastly one for viewing the status of the readiness monitors.)

You clear the DTCs even though none are present to reset the engine controller's learned fueling (long term fuel trims is one learned fueling item) to their defaults (zero adjustment). This undoes any mis-learned fueling due to a malfunction component, in this case the suspected MAF.

You want the clear option and follow the on screen instructions for clearing the DTCs. Generally a tool recommends the engine ignition key be turned to on but the engine remain off but I never bother with this. That is I just start the engine then after the tool connects to the vehicle navigate to the clear DTCs menu and hit the keys until the operation is complete and the light goes out.

However, in the case of a possible bad MAF and the 'wrong' learning that may have been done by the engine controller based on erroneous info supplied by the MAF you may want to with the MAF disconnected clear the DTCs before starting the engine. If the MAF is really at fault the learning may be so far afield that the engine's cold start may be a bit scary at start up unless the DTCs (and learned fueling) is cleared (reset).

Or not.

Beware the check engine light may come on shortly after the start up (especially if the engine runs rough) so do not immediately dispair. Read the DTCs and write them down. They may be related to the MAF being disconnected or they may even be misfires. The latter arising from the way wrong learned fueling that was present when the engine was first started.

You can then of course clear the DTCs again.

If the engine reacts though with rough running or behaves in a uncharacteristic fashion the MAF may not be the problem and there's something else wrong.

Sincerely,

Macster.

Bryce

What's the chance these symptoms could be caused by boost leaks on the driver side turbo system? That would explain all the misfires being on one side?

Macster

It is possible.

But the freeze frame error code and freeze frame data helps to id the possible cause of the problem and can thus help one confirm or eliminate what you suggest.

If a misfire error code is the freeze frame cause then the freeze frame data has some value in determining when the misfire(s) occured.

If the data indicates the engine was operating at a rpm/load level during which boost was being made (and IIRC there's even an intake manifold absolute pressure freeze frame Pid (parameter Id) available) then certainly a leak in the intake system that allows boost to escape is a possibility.

When my Turbo generated a check engine light the other day it was due to a some misfires and the freeze frame was frozen based on the P0300 error code. The freeze frame data indicated to me the misfires occured almost immediately after cold engine start. Rpms were IIRC 1100 and the coolant temp was quite low among other things.

Besides, I had the benefit of noting when the check engine light came on and it came on shortly (within seconds) after I started the cold engine. Additionally upon engine start I heard the serpentine belt squeal. This was the result of the car sitting outside in the (heavy) rain all night at a motel parking lot.

Anyhow, no way any boost was being made then. Of course, an intake leak might allow air in as well as boost to escape, but misfires generally are due to some other cause other than intake leaks under boost or at any other time.

Unless you tell me the car's intake system has been mod'd or recently been touched. Then an intake air leak becomes a more likely possibility, simply because the last thing touched is the first thing suspected when problems appear.

Sincerely,

Macster.

Bryce

Mechanic says it could be variocam issue, oil pump, possibly something more esoteric. Said he wants to talk to a few shops and Porsche rep before trying anything. Recommends garaging it pending more research. He said it's definitely running lower oil pressure on driver side, and boosting it causes misfires.

Oil pump or variocam is $$$.

Kevin

Bryce, please read this thread> https://rennlist.com/forums/996-turb...ode-p1325.html

You might have the variocam camshaft sealing ring failure. This will allow alot of oil pressure to escape. A faulty intake lifter tappet can give you a random misfire.

I highly doubt that your oil pump is failing. The exception would be IF alot of metal was ingested from a internal component failure.

The oil pressure and miss can be tied together. If you look at Porsche diagnostic flow chart, you need to check your plugs and coil packs first. Changing them last year or whenever doesn't discount a possible component failure. The next thing on the list is to make sure that you don't have a intake leak. You have to pressurize the intake system. Pump up the system to 20PSI > it has to hold. Then you check your injectors and fueling. A faulty fuel pump assy will give you missfires.

The irratic oil pressure needs to be looked at. It is either a electrical issue or a internal engine issue.

BTW, this would be a case where I would be recommending Mobil 1 TDT 5W40 and multiple oil and filter changes.